1. Field Of The Invention
This invention relates to automatic pneumatic tire inflation and deflation systems and, more particularly, to a system of that type having remotely controlled inflation and deflation means fitted on the wheel upon which the tire is mounted.
2. Background Of The Invention
In vehicles equipped with pneumatic tires, the potential for significantly improving the mobility of the vehicle by deflating the tires to increase the "footprint" of the tire is well established. For military vehicles, in particular, survivability and mobility could be enhanced during emergency situations by the provision of quick tire deflation for soft terrain mobility and rapid reinflation for resumed roadway travel. In addition, a system for accomodating slow leaks that would maintain the tires at their optimum pressure would result in further benefits in improved vehicle performance and extended tire life. The availability of a full spectrum of tire inflation pressure settings not only would optimize weak soil performance but also rough road dynamic attenuation.
2. Description Of The Prior Art
Automatic pressure control systems for pneumatic tires comprising pressure generating means mounted on the body of the vehicle for providing air under pressure through conduits to the vehicle wheels for inflating the tires are disclosed in the prior art by E. F. Maas, W. R. Paul, and H. Brockmann in U.S. Pat. Nos. 1,827,662; 2,579,048; and 4,313,483 respectively. Unlike the subject system in which the pressure generating means are "add-on" elements which can be readily fastened directly on the wheels of the vehicle, the aforementioned prior art systems would require that they be designed into the vehicle. Further, those systems necessarily require air-supply connections to rotating members for the delivery of air under pressure to the wheels and tires. Leakproof connections to rotating members, particularly under the service conditions to which motor vehicles are routinely subjected, introduce complexity and problems with reliability that militate against the value of those systems.
The prior art also teaches wheel-mounted tire inflation systems as evidenced by U.S. Pat. Nos. 1,127,079; 1,338,337; 2,211,935; and 3,511,294, F. Nielsen, A. W. Stonestreet, C. W. Parker, and A. J. Bepristis et al. respectively. Both F. Nielsen and C. W. Parker teach wheel mounted air pumps having their output connected into the tire. Nielsen and Parker teach pump mechanisms having an arrangement of drive eccentrics and weights which operate when the wheel on which they are fitted rotates such that air under pressure to their associated tire is furnished thereby. However, not only are the pump mechanisms bulky and mechanically complicated, but they will be prone to unacceptable levels of noise ad vibration. Although Stonestreet terms his invention a pneumatic tire inflating mechanism and provides an annular reservoir which is maintained at the normal operating pressure of the tire, the mechanism disclosed operates to relieve back to the reservoir over-pressure in the tire resulting from impacting an obstacle. Stonestreet thus teaches a shock absorbing mechanism, not a tire inflating system per se. In the emergency tire inflation system of A. J. Bepristis et al., an annular reservoir of air or chemical reagents under pressure is carried in the "well" of the wheel rim for providing pressurized air or foam as required for inflating a tire mounted on the wheel. Unlike the subject invention which can be fitted without modification on existing vehicle wheels, a wheel having a locking ring on one side of its rim has to be provided to use the system of Bepristis et al. Bepristis et al. thus do not provide a simple add-on system that can be used to retrofit existing vehicle wheels to give them an automatic inflation pressure regulating capability.